Polymers may be blended to achieve new compositions with desirable properties; however, the vast majority of polymers are immiscible with each other. Attempts to blend polymers often results in heterogeneous multi-phase compositions when the polymers are immiscible with each other. Such compositions may exhibit several thermal transition temperatures (Tg, Tm), usually exhibit poor mechanical properties, and suffer from delamination and/or aesthetical defects.
Indeed, the mechanical properties and ease of processing of a particular blend depend on the degree of compatibility of the polymer components. The main polymer component is usually referred to as the continuous phase or matrix, whereas the minor polymer component is typically defined as the dispersed phase. The degree of compatibility can be characterized by the dimensions of the dispersed phase in the continuous phase and the level of adhesion between the matrix and the dispersed phase. Certain highly immiscible blends are impossible to extrude in normal operating conditions due to a high die swell and are therefore not commercially available.
Blends of PAEKs and PES are an example of such a blend. PAEKs are known to have excellent strength and chemical resistance, and PES is known to have excellent mechanical properties such as a high modulus and a low melt viscosity advantageous for making shaped articles with thin portions. Therefore, it would be desirable to blend these polymers to achieve a combination of their beneficial properties; however blends of PAEKs and PES are known to be highly immiscible, exhibiting extreme die swell and low melt strength. As a result, there are currently no commercial blends of these polymers.
Accordingly, a need exists for new blends of PAEKs and PES having increased compatibility.